1G2 Dr. Waldie — Filtration of Hxighli wafer. [Augi IT, 



differs from both in that the infra-orbital lobe is not united to the front. 

 The external maxillipeds are similar in form to those of the latter but in the 

 mode of insertion of the three terminal joints of these appendages Hylceo- 

 carcinus diners from both genera, forming a transition from the one to the 

 other : in Gecarcinus the third joint completely hides the terminal ones which 

 are inserted on its inner face ; in Hylceocarcinus it hides all but the external 

 ed o, e of the first of these joints : and in Pelocarcinus these joints are insert- 

 ed at the middle of its anterior margin and are completely uncovei^ed. In 

 Jli/heocarciuus, as in its New World allies, the dactylopodites of the ambu- 

 latory legs are armed with six rows of spines. 



A male and a female were taken by the author on Treis Island, Nico- 

 bars, and another male by Mr. A. 0. Hume, C. B., on Narcondam Island, 

 Andamans. 



The paper will appear in the next number of the Journal. 



4. Descriptions of new species of JJnionidce. — Bi/ W. Theobald. 

 This paper will appear in Part II, No. 4, of the Journal. 



Dr. Waldie made the following brief remarks on some investiga- 

 tions he was engaged in, regarding the filtration of the water of the river 

 Hughii during the rainy season — 



The filtering operations at Palta for the water supply of Calcutta have, 

 during the rainy season, been attended with great trouble and difficulty, 

 and remedies had been proposed for this based upon experience in water 

 filtration in England. He, the speaker, however, who had long been ac- 

 quainted with the difficulty, had always maintained that it arose from a 

 peculiarity in the water itself, and that conclusions drawn from experience 

 with English river water were not applicable to the case. Hitherto he had 

 not been able to support his view otherwise than by arguments drawn from 

 the difference of circumstances in the two cases and by the actual facts 

 observed in the filtration. A few days ago a new idea occurred to him by 

 which he thought it probable that the nature of the peculiarity of the water 

 might be explained, which he had immediately put to the test of experi- 

 ment, and with such a satisfactory result that he intended to follow it up, 

 and would, with permission, bring it before the Society at the first oppor- 

 tunity. The title of the proposed communication would probably be, 

 " An experimental enquiry into the characteristics of the nmddy water of 

 the Hughii during the rainy season, with reference to its purification." 



The President announced that there would be a recess of two months 

 and that the next meeting would be held in the month of November. 



